In the case of salient-pole machines, such as salient-pole generators, the cooling of the field winding of an associated salient-pole rotor often presents considerable technical difficulties. Whilst a whole series of technically unobjectionable and functional proposals already exists for passing cooling air into pole gaps in the salient-pole rotor, the previously known measures for field coil cooling, i.e. the dissipation of the heat in order to limit the temperature of the field coils of salient-pole machines, have until now been largely unsatisfactory. For example, EP 0 415 057 B1 describes an arrangement for the forced supply of a cooling medium into a gap between a pole core of the rotor body and the field coil, in which a guiding device is provided in the gap between the pole core and the field coil which splits the gap into two areas which are freely connected essentially only at that end of the gap which is on the pole-cap side and otherwise have a flow passing through them successively. Such a guiding device is comparatively complex in terms of manufacturing, however, and requires special, correspondingly adapted fitting.
DE 198 10 628 A1 discloses a ventilation system for the field winding or field coil of large salient-pole machines, in which flow paths are also formed at the top of flat copper conductors of the field coil parallel to the flow path in the pole gap. The parallel flow paths thus formed pass through all the flat copper conductors and the associated insulating layers. However, the flow paths weaken the field coils and, under certain circumstances, do not result in the expected cooling performance.